From the viewpoint of construction, the ion generating portion of the conventional static eliminators are shaped in the form of box or rod.
From the viewpoint of discharge property, there is a self-discharged static eliminators. The self-discharged static eliminator uses conductive thin fibers. The discharge occurs from the leading ends of the fibers when the difference of static potential between the fibers and the object to be discharged or the fibers themselves rises above a certain value, which results in the cut-down of static electricity of the charged object. The self-discharged static eliminator is used to discharge static electricity of the charged objects by approaching the static eliminator to the charged objects. The operators in the factory wear the self-discharged static eliminators to discharge the static electricity from themselves and cut down the charge.
Since the ion generation portion of the static eliminator of the former is shaped in the form of box or rod, a large space is required to install it. Therefore, since the static eliminator can not be installed in the machine or in the narrow gap, the static electricity can not be eliminated in the area of static generation.
With the self-discharged static eliminator of the latter, the self-discharge does not occur until static electricity is accumulated and then static potential difference goes over a certain value, about 700 V, and the self-discharge stops when static potential difference goes below the certain value, about 700 V, and therefore the residual static electricity of about 700 V always remains.
FIG. 18 shows a conventional self-discharged static eliminator. A self-discharged static eliminator 300 comprises a line-like or rod-like conductor or a plate-like or fiber-like conductor body 302 provided with whisker-like conductors 304, and is called “eliminator brush” or “arm band”. The eliminator brush is not necessary to have electronic device separately and can eliminate static electricity. That is, without application for energy from the outside, the eliminator can discharge static electricity and therefore is called self-discharged static eliminator.
On the principle of operation, when the eliminator brush is disposed opposite to the objective 306 to be discharged such as a work made of paper, film, or sheet, and then the distance D is shorten, the electric field on the leading ends of whisker conductors become large and then insulation of air can be held. Finally, corona discharge starts and then air ions in the opposite polarity of the work are induced.
FIG. 19 shows a graph of elimination property of a conventional self-discharged static eliminator. The curve line indicated at “static elimination property of prior art” on the graph shows that when the elimination brush is approached to the work bearing static potential of 5 kV, the corona discharge starts and the static potential gradually decreases. When the static potential decreases to about 1 kV, the electric field on the leading ends of whiskers of static eliminator is weaken and finally the corona discharge stops. Since at that time static elimination ends, the static electricity is not completely eliminated and the residual static electricity of about 1 kV remains.
It is desirable that static elimination is made enough to eliminate residual static electricity as shown by the curve line indicated at “static elimination property of invention” in FIG. 19.
With the fiber-like static eliminator as shown in FIG. 8, plus electrodes and minus electrodes are arranged in line, respectively. These electrodes are not disposed oppose to each other and are disposed in zigzag. In this case, since, for example, each of minus electrodes is equally applied with sucking force from plus electrodes on both sides, the leading ends of electrodes are not approached, and thus spark discharge or short due to approaching of electrodes does not occur.
However, with the conventional DC type of fiber-like static eliminator as shown in FIG. 31 in which a multiplicity of fiber electrodes are disposed in parallel on support on its opposite sides, if the discharge electrodes project from the end of support, the leading ends of discharge electrodes approach to each other due to static force, which would result in the spark discharge or short.
More specifically, referring to FIG. 31, a fiber-like static eliminator 210 comprises a multiplicity of plus fiber electrodes 214 and a multiplicity of minus fiber electrodes 216 disposed in parallel on support 212 on its opposite sides. Both electrodes 214 and 216 are power supplied from conducting electrodes 218, and the leading ends of plus and minus electrodes 214 and 216 project from the end of the support 212.
Therefore, it is an object of the present invention to provide a tape type of static eliminator which can be installed in a small space or gap and does not generate the stoppage of discharge even when the static potential goes down below about 700 V.
It is anther object of the present invention to provide a self-discharged static eliminator, hereinafter referred as to “static eliminator” or “eliminator brush” which can eliminate static electricity with ease by small power until the residual static electricity is removed.
It is a further object of the present invention to provide a DC type of fiber-like static eliminator which prevents spark discharge or short.